Electrochemical cells using metal as a fuel are known. Electrochemical cells using an electrolyte, a solution of solvent molecules and solute ions, as an ionically conductive medium are also known. Electrolytes maintain ionic conductivity because solvent molecules solvate with solute ions due to thermodynamic interactions between those species. In an electrochemical cell using metal as the fuel, metal fuel is oxidized during discharge to reducible metal fuel ions at a fuel electrode functioning as an anode, the oxidized metal fuel ions remain in the electrolyte solution in reducible form (either as solvated ions, or combined with other ions, such as in a molecule or complex). During charging, the reducible metal fuel ions are reduced to metal fuel at the interface between the electrolyte and the fuel electrode, which is now functioning as a cathode—the metal fuel thus plates the fuel electrode by this process, known as electrodeposition.
The electrolyte solution may comprise an additive. Electrochemical cells using an additive in the electrolyte are known. Examples of such devices are shown, for example, in U.S. Pat. No. 6,027,827 and United States Patent Application Pub. No. 2009/0061293, which are incorporated herein in their entirety. Additives for different electrochemical systems may include nitrite, lithium iodide, carbon dioxide or sulfur dioxide. Benefits of additive use in an electrochemical cell may, for instance, improve the electrochemical reactions by means of forming an ionically conductive layer on an electrode or decreasing wettability issues of electrodes. Yet, the additive may, in result, impede the function or efficiency of the electrochemical cell. For example, an electrolyte in a regenerative cell that promotes quick electroplating may concurrently promote less dense electroplating of the metal fuel on an electrode. Less metal fuel is then available as energy for the electrochemical cell reactions during discharge.